ArrayBuffer是一种mutable的数据容器，相对于Array来说，最大的区别就是可以自由增删元素。当ArrayBuffer构建完毕后，还可以转换为immutable的Array容器。

An ArrayBuffer is like an array, except that you can additionally add and remove elements from the beginning and end of the sequence. All Array operations are available, though they are a little slower due to a layer of wrapping in the implementation. The new addition and removal operations are constant time on average, but occasionally require linear time due to the implementation needing to allocate a new array to hold the buffer's contents.

示例代码如下：

import scala.collection.mutable.ArrayBuffer
object S014_ArrayBuffer {

	def main(args: Array[String]): Unit = {
		val ab=ArrayBuffer[Int]()
		ab += 100
		ab += 200
		ab.append(300)
		ab.prepend(10)
		ab.insert(2, 150)
		ab.foreach(println)
		for(x <- 1000 to 10000 by 100){
			ab.append(x)
		}
		val ary=ab.toArray
		for(i <- ary){
			println("ary: " + i.toString)
		}
	}

}

参考资料：

http://www.artima.com/pins1ed/collections.html